TY - CONF A1 - Bakir, Nasim T1 - In situ determination of the critical staining condition for solidification cracking during laser beam welding N2 - Using a novel optical measurement technique together with the OF algorithm, a two-dimensional deformation analysis during welding was conducted. The OF technique was the first of its kind to provide a measurement of the full strain field locally in the immediate vicinity of the solidification front. The local critical strain and strain rate in vicinity of the solidification front has observed 1.57%, 28 %/s, respectively. T2 - Lane 2020 CY - Online meeting DA - 07.09.2020 KW - Optical measurement technique KW - Laser beam welding KW - Solidification cracking PY - 2020 AN - OPUS4-51741 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Brunner-Schwer, C. A1 - Graf, B. A1 - Rethmeier, Michael T1 - Entwicklung des hybriden Auftragschweißens als leistungsfähigen Bechichtungsprozess für Korrosions- und Verschleißschutzschichten N2 - Dieser Beitrag stellt Ergebnisse der Untersuchungen zum Auftragschweißen als Plasma-Laserstrahl-Hybrid-Prozess dar. Es hat sich gezeigt, dass ein Laserstrahl, der in einer gemeinsamen Prozesszone mit einem Plasma-Pulver-Auftragschweißprozess vorlaufend angeordnet ist, diesem Prozess eine erhebliche Geschwindigkeitssteigerung sowie eine Verbesserung der Stabilität ermöglicht. Der Hybrid-Prozess konnte mit Verschleißschutzwerkstoffen sowie dem Korrosionsschutzwerkstoff Inconel 625 bei Vorschubgeschwindigkeiten von bis zu 10 m/min erfolgreich validiert werden. Im Hinblick auf die aktuellen Entwicklungen zu Hochgeschwindiglceits-Laserstrahlauftragschweißen kann der Plasma-Laserstrahl-Hybrid-Prozess zwischen diesen und den konventionellen Verfahren eingeordnet werden. KW - Auftragschweißen KW - Hybridschweißen KW - Laserstrahlschweißen KW - Schutzgasschweißen PY - 2020 SN - 0036-7184 VL - 72 IS - 8 SP - 474 EP - 475 AN - OPUS4-51321 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Meng, Xiangmeng T1 - Numerical study of additional element transport in wire feed laser beam welding N2 - The distribution of the alloying elements from the filler wire in laser beam welding plays an important role on the property of the final weld. In this study, the transport phenomena in the wire feed laser beam welding are investigated numerically. A three-dimensional transient heat transfer and fluid flow model coupled with free surface tracing and element transport is developed. A ray-tracing method with local grid refinement algorithm is used to calculate the multiple reflections and Fresnel absorption on the keyhole wall. The filler material flows backward along the lateral side of the weld pool, and subsequently flows forward along the longitudinal plane to bring the additional alloying elements to the forepart of the weld pool. The occurrence of the bulging phenomenon may further prevent the downward transfer of the additional elements to the root of the weld pool. The numerical results show a good agreement with the experimental fusion line and element distribution. T2 - 11th CIRP Conference on Photonic Technologies [LANE 2020] CY - Online meeting DA - 07.09.2020 KW - Laser beam welding KW - Element transport KW - Filler material PY - 2020 AN - OPUS4-51568 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pittner, Andreas A1 - Fabry, Çağtay A1 - Hirthammer, Volker A1 - Rethmeier, Michael T1 - Open Science in der Schweißtechnik N2 - Darstellung der aktuellen Situation sowie des Potenzials von Forschungsdatenmanagement und OpenScience in der Schweißtechnik. T2 - WelDX - Open Science Seminar CY - BAM Berlin, Germany DA - 04.03.2020 KW - Digitalisierung KW - Schweißtechnik KW - OpenScience KW - Forschungsdatenmanagement PY - 2020 UR - https://www.bam.de/Content/DE/Veranstaltungen/2020/2020-03-09-weldx-open-science-seminar.html AN - OPUS4-51857 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Straße, Anne T1 - Measurement of thermal cycle and layer hight at multi-pass build-up during LMD-Process N2 - The shape of the parts, created by the technology of laser metal deposition (LMD), is influenced by various parameters, for example, the power and diameter of the laser source spot. The contribution of energy from the laser affects the temperature distribution in the formed layers. The changing temperature in the working area entails a change in the geometry of the layers and affects the stability of the process. In this paper, experiments on the measurement of temperature cycles in the DLMD process with different directions of the filling track are carried out. An infrared camera was used to measure thermal cycles. The calibration of the acquired data (i.e. correspondence table between the intensity of thermal radiation of the material and the absolute temperature) was done with help of two-color pyrometer ex situ and in situ measurements. The experiments are carried out on two materials 316L and Inconel 718. The effect of the maximum temperature on the layer height is shown, and thermal cycles in the formation of layers for different filling strategies are presented. T2 - 1st Workshop on in-situ Monitoring and Microstructure Development in Additive Manufacturing CY - Online meeting DA - 11.12.2020 KW - Laser metal deposition KW - AISI 316L KW - Alloy 718 KW - Thermography PY - 2020 AN - OPUS4-51816 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bachmann, Marcel A1 - Artinov, Antoni A1 - Meng, Xiangmeng A1 - Rethmeier, Michael T1 - Numerical study of the bulging effect in deep penetration laser beam welding N2 - This article is devoted to the study of the bulging effect in deep penetration laser beam welding. The numerical results of the investigations are based upon experimental results from previous studies to reveal the relationship between the bulging effect and the hot cracking formation, as well as the mixing of alloying elements in the weld pool. The widening of the molten pool in its center area can be observed in full penetration as well as in partial penetration welds on 8 mm and 12 mm thick structural steel plates, respectively. The weld pool shape is extracted from the simulations to evaluate the extent of the necking of the solidification line as well as the bulging phenomena and its influence on the hot cracking phenomena. Relying on an earlier numerical study utilizing a fixed keyhole, simulation models considering a dynamic keyhole are developed thereto. Additionally, the mixing behavior of alloying elements during partial penetration is investigated. The link between the bulge and the studied phenomena is found to be significant. T2 - Lasers in Manufacturing Conference 2021 CY - Online meeting DA - 21.06.2021 KW - Deep penetration laser beam welding KW - Welding simulation KW - Solidification cracking KW - Bulging effect PY - 2021 SP - 1 EP - 8 AN - OPUS4-52848 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bachmann, Marcel T1 - Numerical studies of keyhole dynamic behavior during the laser beam welding with an oscillating magnetic field N2 - The formation of keyhole induced porosity (Process porosity) during laser beam welding (LBW) is mainly associated with the dynamic keyhole behavior. Experimental studies have confirmed that the application of a magnetic field can effectively suppress process porosity. However, there is still no quantitative evidence supporting that this suppression mechanism involves a direct influence of the magnetic field on the keyhole dynamics. In this paper, a novel keyhole reconstruction algorithm is developed and incorporated into a three-dimensional transient multi-physics coupled numerical model to study the dynamic keyhole behavior under the influence of an oscillating magnetic field. This keyhole reconstruction algorithm accurately reproduces the 2D time-averaged keyhole shape, effectively capturing the keyhole tailing and the backward shift of its centroid on the keyhole top. The application of an oscillating magnetic field reduces the keyhole diameter and enhances its stability. The frequency of keyhole collapse is reduced under the influence of a magnetic field. Additionally, the occurrence of keyhole collapses with long duration is significantly reduced in the presence of a magnetic field. T2 - 78th IIW Annual Assembly and International Conference CY - Genua, Italy DA - 22.06.2025 KW - Laser beam welding KW - Magnetohydrodynamics KW - Porosity KW - Numerical simulation PY - 2025 AN - OPUS4-63645 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rethmeier, Michael A1 - Gook, Sergej T1 - Notch impact toughness of laser beam welded thick sheets of cryogenic nickel alloyed steel X8Ni9 N2 - This research work deals with the investigations of the impact toughness of laser beam welded 14.5 mm thick sheets made of cryogenic steel X8Ni9 as a function of preheating. This 9% nickel alloyed steel is widely used in the liquefied natural gas (LNG) industry. An application of highly efficient welding processes such as high-power laser beam welding (LBW) in LNG sector requires an understanding of the interactions between the LBW process parameters and weld properties, in particular the impact toughness. The results show that the original fine-grained martensitic microstructure of the base metal (BM) is significantly changed by melting and crystallization during the LBW, what can lead to a decrease in the impact toughness of the weld metal (WM) below the required level. An optimal preheating temperature range leads to the favorable thermal welding cycle and is of remarkable importance for maintaining the notch impact toughness of laser beam welded joints of these thick steel sheets. A parameter window was identified in which V-notch impact toughness comparable to that of the BM at -196 °C was achieved. T2 - 11th CIRP Conference on Photonic Technologies LANE 2020 CY - Online meeting DA - 06.09.2020 KW - Cryogenic steel KW - Laser beam welding KW - Welding thermal cycle PY - 2020 AN - OPUS4-51750 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Karkhin, Victor A1 - Artinov, Antoni A1 - Bachmann, Marcel A1 - Rethmeier, Michael T1 - Simulation of solidification during laser welding of thin plates T1 - Моделирование процесса кристаллизации при лазерной сварке пластин малой толщины N2 - It is proposed to model the experimentally observed weld pool boundary with superellipses (Lamé curves) and to find the unknown parameters of the curves using optimization methods. It has been shown experimentally that during laser welding of austenitic stainless steel with a thickness of 2 mm at a speed of 20 mm/s, the rear weld pool part has a shape close to triangular which can be accurately approximated by a superellipse. Analytical dependences of the trajectory and growth rate of the crystal and its cross-sectional area on the geometry of the rear weld pool part are obtained. KW - Laser beam welding KW - Plane crystalization KW - Mathematical modeling KW - Superellipse KW - Thin steel plates PY - 2023 DO - https://doi.org/10.34641/SP.2023.1061.4.033 VL - 4 SP - 28 EP - 33 AN - OPUS4-59649 LA - rus AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gook, S. A1 - Üstündag, Ömer A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Verfahren zum fehlerfreien Laserstrahl-MSG-Hybridschweißen geschlossener Rundnähte N2 - In diesem Beitrag werden Ergebnisse der Untersuchungen eines Verfahrens zum fehlerfreien Laserstrahl-MSG-Hybridschweißen von geschlossenen Rundnähten vorgestellt. Das Verfahren zielt auf die Vermeidung von Schweißnahtunregelmäßigkeiten im Überlappbereich einer hybridgeschweißten Rundnaht. Eine Strategie der Prozessführung beim Schließen der Rundnaht wurde entwickelt, mit der ein fehlerfreier Überlappbereich durch die Kontrolle der Erstarrungsbedingungen am Schweißnahtende erreicht wird. Die kontrollierte Wärmeführung wird durch eine Anpassung der Parameter von beiden beteiligten Schweißprozessen, dem Laserstrahl sowie dem Metallschutzgas (MSG)-Schweißprozess, realisiert. Experimentelle Untersuchungen wurden an 12 bis 15 mm dicken Rohrabschnitten durchgeführt. Der Einfluss von Prozessparametern wie der Veränderung des Abbildungsmaßstabs und der Defokussierung des Laserstrahls auf die Erstarrungsbedingungen am Ende der Rundnaht wurde untersucht, um eine optimale Strategie zum Herausführen der Prozessenergie zu finden. Im Rahmen der experimentellen Untersuchungen konnte gezeigt werden, dass eine Defokussierung des Laserstrahls im Bereich zwischen 60 mm und 100 mm über einen kurzen Auslaufbereich der Naht von etwa 15 mm zu einer deutlich besseren Nahtausbildung im Überlappbereich führt. Es konnte eine günstige kelchförmige Schweißnaht ohne eine Tendenz zur Rissbildung erzielt werden. Die Laseroptik mit motorisch angesteuertem Linsensystem ermöglichte dabei eine Vergrößerung des Laserstrahldurchmessers ohne eine Veränderung der Position des MSG-Lichtbogens relativ zur Bauteiloberfläche. KW - Hybrid welding KW - Laser beam welding KW - Pipe manufacturing KW - As-shielded arc welding KW - Weld defects PY - 2021 VL - 73 IS - 3 SP - 116 EP - 121 PB - DVS Media GmbH CY - Düsseldorf AN - OPUS4-52365 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -